1. Field of the Invention
The invention relates to a method for substrate treatment.
2. Description of the Background Art
Copper and its alloys are increasingly being used for metal interconnects in advanced integrated circuit fabrication because they have lower resistivities compared to aluminum and do not suffer from poor electromigration. Copper can be deposited over high aspect ratio via and contact structures using metal electroplating. A typical electroplating method generally comprises vapor depositing a barrier layer over the via or contact, vapor depositing a conductive metal seed layer, e.g., copper, over the barrier layer, followed by electroplating a conductive metal over the seed layer to fill the via or contact structure. Finally, chemical mechanical polishing (CMP) can be used to define a planarized conductive interconnect feature by polishing the electroplated metal layer using a polishing fluid, which may include a chemical and an abrasive.
However, defects may be introduced into the planarized conductive layer after CMP. These defects may include, for example, particulate or chemical contamination, physical damage, discontinuity in the conductive layer, and so on. Therefore, the planarized metal layer is subjected to various post-CMP cleaning or treatment (e.g., thermal or plasma anneal) steps prior to additional processing such as subsequent deposition of a dielectric layer. However, even after post-CMP cleaning or treatment, the surface of the planarized layer may present other problems in subsequent processingxe2x80x94e.g., vulnerability to chemical corrosion, or failure to provide a good adhesive surface for a subsequently deposited layer such as a dielectric layer.
Therefore, there is an ongoing need for a method of post-CMP treatment of a metal layer.
The present invention generally provides a method of treating a substrate, comprising forming a metal-containing layer on the substrate during substrate cleaning. In one embodiment, a substrate is subjected to chemical mechanical polishing prior to being treated according to embodiments of the invention. During substrate cleaning following chemical mechanical polishing, the substrate is exposed to an electroless plating solution (or electrolyte) to form a metal-containing layer by electroless deposition over at least one portion of the substrate, e.g., over one or more copper features on the substrate. The electroless deposition of the metal-containing layer may be accomplished by either spraying the electroless plating solution on the substrate, or by immersing the substrate in a cleaning bath containing the electroless plating solution.